The basic or

fundamental concepts of geomorphology are as follows:

1. The same physical processes and laws that operate today operated throughout geologic

time, although not necessarily with the same intensity as now.

This is the important principle of geology and is known as the principle of

uniformitarianism. It was first enunciated by Hutton in 1785. ACCORDING to Hutton "the present is

the key to the past". According to him geologic processes operated throughout geologic time with

the same intensity as now. We know that it is not true. Glaciers were much more significant during

the Pleistocene and during other periods of geologic time than now; world climates have not

always been distributed as they now are, and, thus, regions that are now humid have been desert

and areas now desert have been humid. There are numerous examples which shows that the

intensity of various geologic processes has varied through geologic time.

2. Geologic structure is a dominant control factor in the evolution of landforms and is

reflected in them.

The major controlling factor in land form development is structure and process. Here the

term structure includes not only the folds, faults etc. but all those ways in which the EARTH

materials out of which land forms are carved DIFFER from one another in their physical and

chemical attributes. it includes such as rock attitudes; presence or absence of joints, bedding

planes, faults, and folds; rock massiveness; hardness of constituent minerals; the susceptibility of

the mineral constituents to chemical alteration; permeability and impermeability of rocks; and

various other ways by which the rocks of the earth crust differ from one another. The term

structure also has stratigraphic implications, and knowledge of the structure of a region implies as

appreciation of rock sequence, both in outcrop and in subsurface, as well as regional relationship

of the rock strata.

In general the structures are much older than the geomorphic forms developed upon

them. Such major structural features as folds and faults may go BACK to far distant periods of

diastrophism.

3. To a large degree the earth's surface possesses relief because the geomorphic

processes operate at different rates.

The rocks of the earth's crust vary in their lithology and structure and hence offer varying

degrees of resistance to the gradational processes. Differences in rock composition and

structures are reflected not only in regional geomorphic variability but in the local topography as

well. The local intensity of particular processes may change notably in response to differences in

such factors as TEMPERATURE, moisture, altitude, exposure, topographic configuration, and the

amount and type of vegetal cover. The microclimatic conditions may vary markedly between a

valley floor and a hilltop, between a northern and a southern exposure, and between bare ground

and that with a heavy vegetal cover. The rate of all weathering, all mass-wasting, all erosion, and

all deposition varies appreciably within rather narrow limits in relation to the influence of local

conditioning factors.